Metallurgical furnace



July 14, 1942. c. E. MORAN METALLURGICAL FURNACE Filed Aug. 3, 1940 2Sheets-Sheet l 1 f I II 1 INVENTOR. CLARENCE E. MORAN BY A'ITORNl't'ZJuly 14, 1942. c. E. MORAN 2,289,719

' METALLURGICALVFURNACE Filed Aug. 5, 1940 2.Sheets-Sheet 2 l3 I6 I 51'0 LII l's INVENFOR. CLARENCE EMORAN BY MAW Ail ATTORNEYS.

Patented July '14, 1942 NT OLFFIICE METAILURGICAL FURNACE Clarence E.Moran, Canton, Ohio, assignor to Radiant Combustion, 1110., Warren,Ohio, a corporation of Ohio Application August '3, 1940, Serial No.350,437

1 Claim. 01. 263-43) This invention relates to a metallurgical furnace,and more particularly to an improved construction of furnace havingnovel means forsupplying heat to the heating chamber thereof.

The problems incident to the construction and operation of metallurgicalfurnaces using gas as a fuel, and which are adapted to heat metal tohigh temperatures, are many and well known. Obviously, the mostdesirable way to supply heat to a furnace is to feed the fuel into andburn the same in the heating chamber of the furnace. In those furnaceconstructions where the fuel is fed through a nozzle and burned in theheating chamber which also serves as a combustion chamber, it isnecessary to make the heating or combustion chamber of a sizeconsiderably larger than required for the purpose of holding thematerial to be heated, in order to enable complete combustion of thefuel to take place.

An additional objection to this type of furnace is that the insidesurface of the walls forming the heating chamber is directly subjectedto the action of the burning fuel, and care must be taken to preventmelting of the firebrick from which such walls are made. Another featurewhich renders this type of furnace objectionable for many purposes, suchas its use as an annealing furnace, is that, in providing the necessarydraft to insure proper combustion of the fuel, the furnace will not beuniformly heated throughout and there will be relatively hot and coldspots therein due to the uneven movement of the burning gases throughthe furnace under the influence of the draft.

Accordingly, the tendency of the art,;in many Y furnace constructionsfor metallurgical purposes,

has been to abandon the more eflicient method of heating by convectionand rely on the more expensive and lesser efficient heating furnacesemploying radiation to effect the desired heating in order to provide -afurnace" which may be heated uniformly throughout and which will not beunnecessarily large in size. Well known examples of such furnaces arethe electric resistance furnace, electric arc type furnace, and thosefurnaces employing muflies or heat covers which are heated to a red heatand operate to keep the burning gases out of contact with the materialbeing heated and the walls of the furnace.

One of the principal objects of this invention is to provide ametallurgical furnace construction in which the heating fuel is feddirectly into the furnace in such manner as to enable the employment ofboth radiation and convection in heating the contents of the furnace.

A further object is to provide a metallurgical furnace having a novelform of burner for gas fuel which will permit a reduction in size of thefurnace, provide uniform heat throughout the furnace, and enable theheat loss through the walls to be reduced to a minimum.

A further object is the provision, in a furnace of the characterreferred to, of furnace walls having a plurality of fuel burners mountedtherein in such manner as to constitute a substantial part of the totalwall area.

A further object is to provide, in a furnace of the character referredto, a plurality of surface burners mounted in the walls of the furnacein such manner as to constitute a substantial part of the total wallsurface area, the surface bumers comprising porous refractory diaphragmsthrough which fuel is fed into the furnace and burned to produce aheating effect over the entire surface area of the diaphragms.

To the accomplishment of the foregoing and related ends, said invention,then; consists of the means hereinafter fully described and particularlypointed out in the claim.

The annexed drawings and the following description set forth in detailcertain mechanism embodying the invention, such disclosed meansconstituting, however, but one of various mechanical forms in which theprinciple of the invention may be used.

In said annexed drawings:

Fig. 1 is a top plan view of a furnace constructed in accordance withthe principles of this invention, a part being broken away centrallythereof and shown in section;

Fig. 2 is a central longitudinal vertical sectional view of the furnaceshown in Fig. 1;

Fig. 3 is a front elevational view of the furnace shownin-Fig. 1, a partbeing broken away centrally thereof and shown in section;

Fig. 4 is a vertical sectional view of a modified form of furnace; and

Figs. 5 and 6 are transverse sectional views illustrating thefundamental construction of the burners to be used for supplying heat tothe furnace.

In the drawings, the numeral I designates as a whole a furnace having abottom 2, side walls 3 and 4, a top 5, an end wall 6, and a front doorclosure member I. The front door closure member 1 is preferably 'of thecounterweighted type mounted for vertical movement in channels 8 to andfrom closed-position. The furnace is also provided with a metallic sheetmetal protective covering 9.

' The bottom I is carried on beams l mounted on suitable supportingmembers II. The side walls of the furnace l are reinforced by verticalbeams l2, connected at their tops by cross beams l3 and at the bottom bytie rods l4. The front and rear ends of the furnace are likewisereinforced by beams 14' connected at the top and bottom thereof by tierods l5. Supporting channels l6 are secured to the under side of thetrans-" verse beams l3 to which the upper ends of a plurality ofprotecting rods II are connected. The

protecting rods l1 extend through the interior of the furnace for apurpose to be described, and have their lower ends suitably secured tothe lower surface 18 of the bottom of the furnace I.

A floor is provided for supporting the material to be heated in thefurnace and comprises a plate l9 formed of suitable alloy steel carriedby a plurality of supporting blocks 20 resting on the upper surface 2|of the bottom 2 and spacing the plate I!) from the upper surface 2|. Thesupporting blocks 20 are spaced from each other, as best shown in Fig.1, to provide spaces through which the hot gases may pass in a manner tobe described.

A plurality of burners 22 are mounted in the walls 3, 4 and 6 forsupplying heat to the furnace I. The burners 22 are provided with burnersurfaces 23 in alignment with the interior surface of the furnace, asbest shown in Figs. 1, 2 and 3. It will be noted that the combined areaof the burner surfaces 23 occupies a substantial portion of the totalwall surface defining the heating chamber within the furnace I. Theburners 22 are preferably constructed in accordance with the disclosureof my Patent No. 2,194,- 208, issued March 19, 1940. This constructionis illustrated in Figs. and 6 and comprises a hollow metallic casing 24in which is mounted a diaphragm 25 formed of a plurality of porousrefractory slabs through which the fuel may be fed from a supply line26. The diaphragm 25 and bottom 21 of the casing 24 are formed toprovide a plurality of passageways 28 at the rear of the diaphragm 25.The passageways 28 are interconnected with the supply conduit 26 andoperate to deliver a combustible mixture of fuel from the supply conduit26 uniformly over the entire back surface of the diaphragm 25. Thecombustible mixture of fuel is fed under pressure through the conduit 26and is forced outwardly through the porous diaphragm 25 and is burneduniformly over the surface 29 thereof in such manner that the surface 29will be heated to a uniform degree of incandescence after the burner hasbeen in operation for a short time.

Although the construction of Figs. 5 and 6 illustrates a diaphragm 25formed of a plurality of porous refractory slabs, it will be understoodthat the diaphragm 25 may be formed of a single porous refractory blockin accordance with the teachings of my aforementioned patent. It willalso be understood that the showing of Figs. 5

and 6 is intended only to illustrate the principles of the preferredconstruction of the burners 22, the particular shape of the burners 22and the manner in which the fuel is fed thereto being different from theconstruction shown in Figs. 5 and 6.

The burners 22 comprise metallic housings 30 mounted in suitableopenings formed in the sides 3 and 4 and end 6 of the furnace l in suchmanner that the surface 23 of the porous refractory block in each casing30 is flush with the interior wall surface of thefurnace. The burners 22are so positioned with respect to the floor or plate I! as to bedirectly opposite the material to be heated, which is placed on thefloor l9. As best shown in Fig. 1, the combustible mixture of air andgas is fed centrally of the burners 22 through conduits 3| connected bybranch conduits 32 and 33 to a suitable source of fuel supply 34, a firecheck valve 35 being interposed betweenthe source 34 and the conduits 32and 33.

The protecting bars I'I extending'through the heating chamber within'thefurnace l are positioned closely adjacent the peripheral edges of thefloor Ill. The bars ll operate to protect the burner surfaces of theburners 22 by preventing movement of the material to be heated from thefloor l9 into engagement with the burner surfaces 23.

The combustible mixture of gas and air is fed to the individual burners22 under pressure, and to permit the escape of the heated gases afterburning, the bottom 2 of the furnace I is provided with vents 36connected with a duct 37| through which such gases may be carried away,a fan or other suitable apparatus (not shown) being provided to assistin the removal of the products of combustion from the heating chamber.By reason of the location of the burners 22, the hot gases will moveoutwardly from. the burner surfaces 23 and then downwardly over thematerial to be heated. After contacting the material being heated, thegases escape to the vents 36 through the space provided between theperipheral edge of the hearth l9 and the side walls of the furnace andthe space between the supporting blocks 20 for the hearth l9. In thismanner, heating by convection is provided through the passage of the hotgases over the material to be heated.

In the modified construction shown' in Fig. 4, the numeral 38 indicatesas a whole a circular furnace having annularly shaped side walls 33 anda removable top 40. The furnace 30 is provided with supports 4| in thebottom thereof for the material to be heated which may be placed in andtaken from the furnace upon removal of the top 40. In this construction,it will be noted that the burners are mounted in such manner as toprovide a plurality of burner surfaces 23 in spaced rows. The burners ineach row are staggered with relation to the burners in the other row toprovide a more uniform heating effect and prevent hot and cold spotslikely to occur if the individual burners were vertically aligned. Allthe burners in the furnace 38 are fed with a combustible mixture of airand gas from branch conduits 42 connectedto a common supply conduit 43.It will be noted that the circular construction of the furnace 38 isparticularly adapted for heating materials circular in shape, such ascoiled steel, indicated diagrammatically by the dotted lines 44 in thedrawings.

The operation of both modifications shown in the drawings is essentiallythe same. The material to be heated is placed on the hearth of thefurnace and a combustible mixture of fuel is fed to the burners 22. In ashort period of time, the burner surfaces 23 will become incandescentand radiate heat directly to the material to be heated. The location ofthe burner surfaces 23, directly opposite the surface on which thematerial being heated is supported, is desirable to provide the maximumeffect from the radiated heat. In addition, the hot gases from theburner surfaces 23 will flow downwardly over the material to the vents36, and such gases will be 2,289,719 operable to apply heat directly tothe material by convection. Accordingly, it will be apparent that theburners 22 enable heat to be supplied directly to the material beingheated by both radiation and convection.

Since the combustible mixture of fuel suppled to the burners 22 issubstantially all burned at the surface 23, it will be apparent that itis not necessary to provide additional space in the heating chamber topermit complete combustion to take place, and the size of the heatingchamber may therefore be merely made suflicient to accommodate thematerials to be heated. v

By reason of the fact that the burner surfaces 23 occupy a substantialportion of the total area of the wall surface defining the heatingchamber, it will be apparent that the burners 2! provide an advantagewith respect to heat losses by reducing the effective area through whichheat may escape from the heating chamber, it being obvious that heatcannot escape through the burner surfaces where the combustion of thefuel takes place. The radiation of a substantial portion of the heatdirectly to the material being heated, together with the manner in whichthe hot gases flow from the burner surfaces 23 to the vents 36, providesan additional element of protection with respect to the firebrick fromwhich the walls of the furnace are made. By reason of the fact thatthehot gases are not directed toward theside walls, the temperature of theinner surface of such side walls is kept down with a consequentreduction in loss of heat through such walls and less danger of thewalls burning.

In connection with the use of the burners 22 as a means of supplyingheat to a furnace by burning gas fuel, I am aware of the fact that theuse of such so-called surface burners has been proposed with respect tocertain types of furnace constructions. However, I believe that I am theflrstto provide a metallurgical furnace, embodying surface burners as aheat source, and which is capable of complete and satisfactory operationunder the conditions and requirements imposed in the metallurgicalheat-treating field.

Other modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards the mechanismherein disclosed, provided the means stated by the following claim orthe equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

A high temperature metallurgical furnace of the character described,comprising top and vertical side furnace walls normally forming anenclosed heating chamber having an opening only in the bottom side, aplurality of porous refractory, gaseous fuel burner diaphragms mountedvertically in said furnace walls with the front faces of said burnerdiaphragms facing inwardly toward said heating chamber and being flushwith the inner surface of said side walls, said burner diaphragms beingspaced from each other both horizontally and vertically in said sidewalls and forming a substantial part of the total inner surface thereof,casings for enclosing the rear faces of each of said burner diaphragms,said casings having a portion of their opposed faces substantially incontact with said diaphragms, gaseous fuel conduits leading to theinterior of said casings, a, plurality of inter-connecting passagewayscommunicating with said conduits and parallel to the rear faces of saiddiaphragms, said passageways being defined in part by said diaphragms,said heating chamber being adapted to receive the gases of combustionfrom the front faces of said burner diaphragms, together with theradiant heat therefrom, and a gas eduction vent connected to saidopening in said bottom side of said heating chamber for the withdrawalof the gases of combustion from said furnace.

CLARENCE E. MORAN.

